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Effect of live yeast on ruminal biohydrogenation. A preliminary in vitro approach

Julien, Christine and Troegeler-Meynadier, Annabelle and Marden, Jean-Philippe and Enjalbert, Francis and Bayourthe, Corine Effect of live yeast on ruminal biohydrogenation. A preliminary in vitro approach. (2009) In: 13th International Congress of the European Society of Veterinary and Comparative Nutrition, 15-17 Oct 2009, Oristano, Sardaigne . (Unpublished)

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Official URL: http://www.esvcn.eu/

Abstract

Introduction : Ruminant dietary feed additives such as live yeasts are used on field because of their ability to induce a better diet utilisation. Even if studies on their mode of action are still going on, references are scarce about live yeast diet supplementation and ruminal biohydrogenation (BH) of dietary lipids in dairy cows. During the ruminal BH, some interesting fatty acids (FA), like conjugated linoleic acids (CLA), are synthesised by bacteria, and then could be transferred to milk. This experiment studied live yeast influence on ruminal BH with an in vitro approach. Materials and methods: Ruminal fluid was sucked out from a rumen fistulated dry dairy cow receiving a hay-based diet (57% hay, 43% concentrates) and divided in 10 flasks containing substrates (starch, hay and urea) and a buffer solution (pH 7). In 5 flasks, live Saccharomyces cerevisiae (1010 CFU/g DM, BIOSAF Sc 47, Lesaffre Feed Additives, France) was dosed at 0.15g per flask. All flasks were incubated kept from light and air in a waterbath rotary shaker at 39°C. Two not incubated control flasks without added fat were realized to determine the initial FA amount. After 6h, the incubated flasks were placed into iced water to stop microbial activity and the content was lyophilized for FA extraction and quantification by gas chromatography. Rates and efficiencies of the three reactions composing BH of C18:2 were calculated1. Data were submitted to an analysis of variance. Results and Discussion : Rates and efficiencies of the 3 steps of BH were not significantly modified by live yeast. Composition of FA of control and treated flaks did not strongly differ. The percentage C16:1+C17:0anteiso was twice higher (P<0.01) with live yeast than control probably because of high amount of C16:1 in live yeast FA profile. Moreover, percentage of C15:0anteiso was lower with live yeast (P=0.03), possibly due to a decrease of Ruminobacter amilophilus, previously observed in vivo with yeast2, since this bacteria is rich in this FA3. No effect was noticed on the percentages of C18 FA (P>0.05), including C18:2 BH intermediates, like trans-11 or trans-10 isomers of CLA and trans-C18:1. Live yeast had no effect in such conditions on the extent of C18:2 (P=0.566) or C18:3 BH (P=0.838), 51% and 54% on average disappeared during incubation, respectively. Conclusion : The fermentative substrate containing hay and the pH were favorable to a high ruminal BH. Live yeast had no effect in such conditions but this work showed that yeast had no adverse effect on BH. Because of live yeast supplementation being advised in case of high concentrate diets inducing ruminal acidosis, further studies will be carried out to investigate live yeast effect on BH in such conditions.

Item Type:Conference or Workshop Item (Poster)
Audience (conference):International conference without published proceedings
Uncontrolled Keywords:
Institution: Université de Toulouse > Ecole Nationale Vétérinaire de Toulouse - ENVT
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
French research institutions > Institut National de la Recherche Agronomique - INRA
Other partners > LESAFFRE (FRANCE)
Laboratory name:
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Deposited By: Annabelle Troegeler

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